Project Summary Chronic lung diseases represent a leading cause of morbidity and mortality worldwide, with symptoms often arising from a progressive loss of lung epithelial cells and respiratory function. While lung tissue transplants can restore respiratory function, these treatments are severely limited by the insufficient supply of donor lungs and the eventual immune rejection of donor tissue. New technologies, including induced pluripotent stem cells (iPSCs) and gene-editing, have opened up the possibility of cell-based treatments where gene corrected patient- derived iPSCs are differentiated and used to replace a patient's lost lung epithelial cells without triggering an immune response. In line with this goal, early experiments using mouse models indicate that lung epithelial cells can be transplanted into injured lungs. However, these early studies utilize rare primary cells or immunocompromised recipient mice, severely limiting their application to clinical cell-based treatments of human lung disorders. Furthermore, it is still unclear whether transplanted cells truly engraft and contribute to pulmonary function or the regenerative response following future injury. The objective of this research proposal is to establish a murine model of cell-based treatment for lung disease through transplantation of mouse PSC (mPSC)-derived lung epithelial cells into syngeneic immunocompetent mice. Unlike previous transplantation models, this work will provide a model of cell-based therapy utilizing a readily available and expandable donor population that is genetically matched to the recipient, theoretically removing the need for immunosuppression. Studies in Aim 1 will compare the gene expression profile, transplant durability, and in vivo differentiation potential of mPSC-derived lung epithelial cells and a control population of transplantable primary lung progenitor cells. As part of this aim, transplant-derived cells will also be directly compared to endogenous cells to determine whether transplant-derived cells contribute to pulmonary function and regeneration. In Aim 2 both primary and mPSC-derived donor populations will be transplanted into SftpcCreERT2/+, ABCA3fl/fl mice, a tamoxifen-inducible and clinically relevant model of respiratory failure due to ABCA3 deficiency and progressive alveolar injury. These mice will then be given sustained tamoxifen treatment to assess whether transplanted cells advantageously and durably contribute to pulmonary regeneration and mouse survival. By addressing these aims this research proposal will not only discern the long-term functional benefits and differentiation potential of PSC-derived transplants, but also provide a model for the development of clinically feasible cell-based therapies for human lung diseases.